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T1G UP

Member Since: 08 Dec 2009
Location: Bath
Posts: 3101

2011 Defender 110 Puma 2.4 XS CSW Orkney Grey

lockers are great...if used correctly. you can still *uck up with them.

ATB are there all the time passively working with the TC and ABS to help you on your way.

uprated shafts and cv's may be required using lockers as you could have a situation where the drive is all through one wheel and pop goes the drive shaft

26th May 2013 9:15am

davew

Member Since: 02 Jan 2012
Location: North Yorkshire
Posts: 888

1990 Defender 90 V8 Petrol PU Auto Rioja Red

zone30 wrote:
Thx, wasn't clear in the description.
I want lockers as it's for offroad use. So air lockers are still the best chooise then?

Yes, a locking diff that you can control is the best option for off road use. http://www.yorkshireoffroadclub.net/

26th May 2013 9:15am

blackwolf

Member Since: 03 Nov 2009
Location: South West England
Posts: 17469

2007 Defender 110 Puma 2.4 DCPU Stornoway Grey

davew wrote:
Just bear in mind ATBs are NOT a locking diff. For off road use they give very little improvement over an open diff. Very occasionally, off road, they will make a difference but only when both tyres on the axle have similar levels of grip, as soon as one wheel slips all the power goes to that wheel just like an open diff.

I had some for a couple of years and used them for trials, in two years of trialling they helped 3 times. In every case it was on a dry surface where both front wheels were scrabbling for grip, similar vehicles with open diffs struggled by comparison.

ATBs work really well on road when you have traction on both wheels limiting wheel spin on wet tarmac, for example. That's why ATBs are popular in track cars. If you're wanting a diff for improved off road use, Torsens are a complete waste of money. If you're towing a heavy trailer on gravel/wet tarmac an ATB will help.

This is an interesting opinion, but (no disrespect intended) is in my opinion complete piffle!

True an ATB is not a locker (nor is it the same as an LSD) but used correctly it works extremely well off road.

If you have one wheel in an axle which has zero traction, then with an ATB you will indeed lose drive to the other wheel. However if there is some resistance to rotation the the bulk of power will be sent to the wheel with most grip. So brake the airborne wheel with TC or your left foot and you're off.

Other advantages - works automatically when you need it, you can steer with one in the front axle, much less likely to break a halfshaft, much less expensive, easier to install.

Ultimately full lockers will outperform anything. Alternatively though when you're stuck with lockers you'll be much more stuck!

Incidentally I run an 86" S1 with ARB lockers front and rear and a 110 Puma with Ashcroft ATBs so do have experience of both. Out and our off-road, lockers, dual purpose, ATBs.

26th May 2013 9:25am

davew

Member Since: 02 Jan 2012
Location: North Yorkshire
Posts: 888

blackwolf wrote:

This is an interesting opinion, but (no disrespect intended) is in my opinion complete piffle! .

Ultimately full lockers will outperform anything.

So it's piffle when I say it but presumably makes perfect sense when you say it ?

http://www.yorkshireoffroadclub.net/

26th May 2013 10:31am

blackwolf

Member Since: 03 Nov 2009
Location: South West England
Posts: 17469

Far from it, but I felt you were a bit harsh on the ATBs. Thousands of people over the years have used torque biasing diffs to great effect off-road and they are a serious contender. That's all I was trying to say.

27th May 2013 8:07am

jst

Member Since: 14 Jan 2008
Location: Taunton
Posts: 8094

2011 Defender 110 Puma 2.4 USW Stornoway Grey

an axle locker you lock you lock yourself is the ideal for off road use but you need to know when and why you would put them in and take them out.

Some prefer the ATB or similar as its an easier install and you dont have to do anything to operate them, but as ^^ they are not a true locker.

the Ashcroft locker was a spin off of the force 9 locker design i believe. its bloody good. has a better engagement system (longer engagement pin over a ARB), better diff mounting system and disengages much quicker than an ARB.

i have ARB F & B on a truck and Ashcroft lockers (Force9) on another. when the ARBs goes tits they will be replaced with Ashcroft units.

Personally i would not run an axle locker without upgrading shafts and CVs Cheers

James
110 2012 XS Utility
130 2011 M57 bespoke Camper
90 2010 Hardtop
90 M57 1988 Hardtop

27th May 2013 6:54pm

zone30

Member Since: 07 Sep 2012
Location: Gent
Posts: 669

2011 Defender 110 Puma 2.4 X-Tech LE Nara Bronze

Great info,guys! Much appreciated!

27th May 2013 7:25pm

landybehr

Member Since: 17 Apr 2013
Location: -D-
Posts: 173

For me the ATBs work very well. I think the terrain that really needs manual controlled lockers is nothing I conquer very often. It depends on how severe you "off-road", doesn´t it.
An advantage the ATBs offer over the manual lockers is that you will still be able to steer the vehicle to where you want to go when they´re active. And, of course, I needn´t think about turning them on or off. Still - nothing for the rock crawler.

27th May 2013 7:50pm

pjh

Member Since: 22 Nov 2010
Location: West Yorkshire
Posts: 126

2011 Defender 110 Puma 2.4 USW Orkney Grey

Quote:
True an ATB is not a locker (nor is it the same as an LSD)

Blackwolf, I agree with all your comments on the ATB, but why would you not describe it as an LSD - I run a Quaife ATB in a Ctaerham and that's exactly the role that I thought it performed?

Interesting thread.

Peter Defender 11MY USW

28th May 2013 1:26pm

blackwolf

Member Since: 03 Nov 2009
Location: South West England
Posts: 17469

pjh wrote:
Quote:
True an ATB is not a locker (nor is it the same as an LSD)

Blackwolf, I agree with all your comments on the ATB, but why would you not describe it as an LSD - I run a Quaife ATB in a Ctaerham and that's exactly the role that I thought it performed?

Interesting thread.

Peter

It was always my understanding that an LSD and an ATB were different albeit similar devices, with the LSD using clutches to limit the difference in rotational speed across the axle (ie based on relative speed not power), and the ATB using helical differential gears and internal friction to achieve a mechanically more sophisticated power split.

Prior to writing this post, however, I did some reading and it is actually considered that an ATB is a type of LSD, so whilst it is true to say that all ATBs are LSDs, there are several other types of LSD.

It seems however that my original understanding is essentially correct. A torque biasing diff directs its power proportionally to the available traction, whereas a generic LSD may use a preset power distribution or operate by limiting the allowed speed difference.

If you look up "limited slip differential" on Wikipedia (link http://en.wikipedia.org/wiki/Limited_slip_differential) there's quite a good explanation of different types.

28th May 2013 5:10pm

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